There is a known technology that communicates with terminal devices via a network to provide services. A known example of this technology is a communication system in which information processing apparatuses that provide services are arranged in multiple base locations and the services are provided by allowing the information processing apparatuses in the base locations to cooperate with each other.
For example, the communication system has a subnet in which local area networks (LANs) in base locations each having a gateway are connected by switches. Then, an information processing apparatus in each of the base locations performs packet communication, via the corresponding gateway by using an Internet Protocol (IP), with a terminal device arranged outside the subnet and provides various services to the terminal device.
Here, a single network address is allocated to the entirety of the subnet. Furthermore, the subnet notifies the terminal device of the address of each gateway in each LAN as the gateway that is used for accessing the subnet. When a terminal device accesses the subnet, the terminal device selects a single address from among the addresses of the gateways that are received as a notification and then sends a packet to a destination that is the selected address.
However, although the subnet notifies the terminal device of the addresses of the gateways that are used for accessing the subnet, the subnet does not notify the terminal device of information indicating which information processing apparatus is installed in which LAN. Consequently, there may be a case in which the terminal device sends a packet to a gateway in a LAN that is different from the LAN in which the information processing apparatus that corresponds to the destination of the packet is located.
At this point, when a packet is sent to a gateway in a LAN that is different from the LAN in which the information processing apparatus that corresponds to the destination of the packet is located, the switch in the subnet transfers the packet to the LAN in which the information processing apparatus that corresponds to the destination of the packet is located. Consequently, packet communication is performed following a roundabout communication path without passing through the gateway in the LAN in which the information processing apparatus that corresponds to the destination of the packet is located.
In order to prevent such packet communication being performed via a roundabout communication path, there is a known technology in which a management server that manages the gateways in the LANs in which information processing apparatuses are installed notifies the gateway of the LAN in which the information processing apparatus that is the destination of a packet is installed. For example, the management server stores therein, in an associated manner, address of gateways and addresses of the information processing apparatuses that are installed in their corresponding LANs. When the management server receives a query about a gateway and an address of an information processing apparatus, the management server notifies the query source of the address of the gateway that is stored in the management server and that is associated with the received address of the information processing apparatus, whereby packet communication that is performed via a roundabout communication path is prevented.
Patent Document 1: Japanese Laid-open Patent Publication No. 2010-098555
Non-Patent Document 1: “VM Mobility Cisco Locator/ID Separation Protocol”, URL: www.cisco.com/web/JP/product/hs/ios/iprs/ipr/prodlit/pdf/at_a_glance_c45-646350.pdf (The “http://” is omitted), Last access on Dec. 7, 2012
However, with the technology described above in which the management server prevents packet communication from being performed via a roundabout communication path, there is a problem in that the processing cost of managing all the addresses of information processing apparatuses and all the addresses of the gateways included in a subnet increase.